Coco coir growing is about the most forgiving of any 'hydroponic' system. I don't know if you even want to call it hydroponic. I have been using it for about a year and its excellent. In flowering, I have my girls in a 3 gal bucket, and I use just plain coco, not vermiculite, no perlite. Your friend may not know it, but vermiculite holds moisture, perlite counter acts the vermiculite. In my opinion, you would be better off not using either. Coco is almost like growing in soil....except it has no nutrients in it for the plants. So, you would be TOTALLY in charge of feeding the plants. I feed my plants with nutrients and feed them once a day, letting the overflow drain to waste (about 20%). Each plant gets about a quart of nutes via a timer. Using coco coir, I can tell you that I have never had a plant 'in shock' after replanting it, which I cannot say for any other method especially hydroton, where I could definitely see them having trouble the first day or two.